1. Field of the Invention
The present invention relates to ceramic nanocomposite powders reinforced with carbon nanotubes, and more particularly to a fabrication process of ceramic nanocomposite powders in which carbon nanotubes are homogeneously distributed in a ceramic matrix without agglomeration of the carbon nanotubes.
2. Related Art
Currently, some researchers have reported fabrication techniques of ceramic composite materials reinforced with carbon nanotubes. For example, in order to improve hardness and fracture toughness of ceramic composite materials, Laurent, C., et al., J. Eur. Ceram. Soc. 18:2005-2013 (1998), Peigney, A., et al., Ceram. Int. 26:677-685 (2000) and Siegel, R. W., et al., Scripta Mater. 44:2061-2064 (2001), developed methods for fabricating carbon nanotubes-Fe-alumina or carbon nanotubes-SiC-alumina composite materials having a weight fraction of carbon nanotubes of 2-15% using a hot pressing process or conventional sintering process.
However, since they employed a simple powder-powder blending method for mixing of carbon nanotubes and ceramic matrix powders to fabricate composite materials, it was difficult to further improve the characteristics of the composite materials to a desirable level. That is, a simple blending of powders for the fabrication of composite materials cannot eliminate factors negatively affecting characteristics of the composite materials such as high porosity, low relative density, etc., resulting from agglomeration of carbon nanotubes, etc. This was because the dispersibility of the carbon nanotubes was not sufficiently taken into consideration during fabrication of the ceramic composite materials.
Therefore, the carbon nanotubes in matrix materials should be dispersed, and this microstructural shape influences the characteristics and sinterability of final ceramic nanocomposite powders to be fabricated. Accordingly, since the improvement in the dispersibility of the carbon nanotubes leads to sound-state composite powders, conventional techniques do not permit the fabrication of composite powders with excellent characteristics. The term ‘sound-state’ used herein refers to the state in which carbon nanotubes are homogeneously dispersed not only on the surface but also in the interior of a ceramic matrix.